This invention relates to a hearing aid that can communicate with a plurality of external devices and, in particular, to a gateway between a hearing aid and a plurality of external devices.
It is known in the art to provide a hearing aid with a Bluetooth® interface for communicating with external devices; e.g. see U.S. Pat. No. 7,174,026 (Niederdränk).
Bluetooth® technology was named after the tenth century king, Harald “Bluetooth” (an Anglicized version of “Blaatand”), who united warring tribes, somewhat the way the Bluetooth® standard unifies different technologies. The standard has been reviewed and revised since its inception and continues to evolve without losing its basic focus.
Bluetooth® technology relates to a spread spectrum, radio frequency (RF) transmission in a globally unlicensed industrial, scientific, and medical (ISM) band at 2.4 GHz. There are three power levels or classes. Class 1 has a maximum power of 100 mW (milliwatts) and a range of approximately one hundred meters. Class 2 has a maximum power of 2.5 mW and a range of approximately ten meters. Class 3 has a maximum power of 1 mW and a range of approximately one meter. Most applications are Class 2. There is a group studying ultra low power Bluetooth® technology.
In the particular application of a hearing aid, power dissipation is a constant problem, particularly for in-the-ear type hearing aids. A small space dictates a small battery. If power dissipation is too great, battery life is reduced. Also, there is a limit on how much heat can be generated in the ear canal of a user without raising the temperature of the hearing aid to an uncomfortable level.
The '026 patent does not disclose power. The named possible signal sources (telephone, PC, television set, stereo system) imply a system that is Class 2 (2.5 mW). This figure is for the power into the final amplifier, sometimes considered the output power to an antenna. In either case, it is not the power for the whole system. A commercially available, Class 2, Bluetooth® module consumes 78 mW during audio streaming (reception). This is a large load for any hearing aid, particularly for an in-the-ear hearing aid.
In view of the foregoing, it is therefore an object of the invention to provide a communication interface or gateway for hearing aids.
Another object of the invention is to provide a low power level communication system for a hearing aid.
A further object is to provide Bluetooth® technology for a hearing aid without adding more than 20 mW to the load on the battery in the hearing aid.